1. Field of the Invention
This invention relates to complexes of zerovalent iron containing phosphite ester ligands and, optionally, diphosphine ligands.
2. Prior Art
Zerovalent iron complexes containing unsaturated hydrocarbon ligands together with either phosphite-ester ligands or PF.sub.3 ligands are known. In addition, pentakis(phosphorus trifluoride)iron, Fe(PF.sub.3).sub.5, is a known compound. Zerovalent iron complexes containing diphosphine ligands in combination with other ligands such as ethylene are also known. No references other than 1 and 8, below, have been found to a zerovalent iron complex containing only phosphite-ester ligands or a combination of phosphite-ester ligands and diphosphine ligands. Other metals, particularly nickel, are known to form zerovalent complexes containing only phosphite-ester ligands.
Specifically:
1. Muetterties and Rathke, Chem. Commun., 850 (1974) disclose pentakis(trimethyl phosphite)iron(O), prepared by sodium-amalgam reduction of tris(trimethyl phosphite)-iron(II) chloride in the presence of excess of trimethyl phosphite. This is an example of a "wet-reduction" method.
2. Green and Whiteley, J. Chem. Soc. (A), 1943 (1971) disclose cyclopentadienetris(triphenyl phosphite)iron(O), made by a wet-reduction method.
3. British 979,778 (Shell, 1965) discloses tetrakis(bicycloheptadiene)(triphenyl phosphite)iron(O), also made by a wet-reduction method.
4. Timms, Advan. Inorg. Chem. Radiochem., 14 121-171 (1972), "Low Temperature Condensation of High Temperature Species as a Synthetic Method". This is a detailed review of the metal-atom-evaporation synthetic technique and a summary of the compounds that have been made by it.
5. Timms, Chem. Commun., 1033 (1969) discloses preparation of Fe(PF.sub.3).sub.5, a known compound, by the metal-atom-evaporation method.
6. Warren et al., Inorg. Chem., 9, 373 (1970), and 11, 452 (1972), disclose 1,3-butadienetris(phosphorus trifluoride)iron(O) and 1,3-cyclohexadienetris(phosphorus trifluoride)iron(O).
7. Mackenzie and Timms, Chem. Commun., 650 (1974) disclose 1,5-cyclooctadienetris(phosphorus trifluoride)iron(O), made by metal-atom evaporation.
8. Meakin, English, Ittel, and Jesson, J. Am. Chem. Soc., 97, 1254 (1975; March 5) describe the nmr spectra of FeL.sub.5 complexes in which L is trimethyl phosphite, triethyl phosphite, and tripropyl phosphite. The complexes were made by wet-reduction procedures.